Put a lid on it!

Alexander GelfandSPECIAL TO THE TRIBUNE

Want to blast your stereo without disturbing the neighbors? Line the walls of your living room with egg cartons and foam mattresses. Desperate to mute the sound of a screaming baby in the apartment below? Lay some rubber mats and carpeting on your floor, and blissful silence will be yours.

Well, maybe not. As it turns out, there are a number of things you can do to soundproof your home. They just don't bear much resemblance to the myths and legends of residential soundproofing that most of us somehow manage to absorb.

The idea behind soundproofing is simple: impede the flow of sound by placing something between its source (for example, that screaming baby) and its target (your ears).

Few things do a better job of blocking sound than sheer mass, which is why lead was once a popular soundproofing material -- and why low-density stuff like egg cartons and old mattresses are pretty much useless. Such lightweight materials may improve the acoustics inside a room by scattering sound, but they will do little to prevent noise from traveling through walls, ceilings and floors in the first place.

Some people claim that pumping your walls full of acoustic insulation will do the trick, but that's unlikely, too. Insulation of any kind will only shave a few decibels off your noise levels. That's a good start, but it probably won't be enough.

The best way to retrofit a room for better sound isolation is to use one of the sound-dampening materials that have come to market in recent years. Several companies, for example, sell specially formulated drywall that turns acoustic vibrations into heat. These products all have different STC ratings, which indicate how much sound-stopping power they possess. STC stands for sound transmission class, and the higher the rating, the better; at least one manufacturer claims that even its least expensive product will reduce sound transmission by 70 percent. A single basic half-inch 4-by-8-foot panel costs around $65, however.

Fortunately, you can replicate the effect of such specialized materials on the cheap by treating ordinary drywall with Green Glue, a gooey compound that similarly transforms vibrations into heat. Green Glue appears to be more effective than many soundproofing materials at stopping low-frequency sounds, which is good news if you are trying to mute the throbbing bass from a stereo subwoofer. It's relatively inexpensive, too; a case of the stuff costs less than $200 and will cover a decent-size wall. Applying it is a bit tricky, though, so if you are not especially handy, you'll probably want to hire a general contractor to do the job.

If noise from the apartment above is the problem, conventional do-it-yourself wisdom advocates creating a "drop ceiling." You can easily fashion a no-frills version by screwing some 1-by-2-inch framing into your existing ceiling and hanging a bunch of drywall panels from them, thereby adding mass along with some dead air space to help block unwanted sound; but you might be disappointed with the results.

For a more serious line of defense, hang the drop ceiling using vibration-deadening resilient sound isolation clips (RSIC). Better yet, use two layers of drywall with a slathering of Green Glue applied with a caulking gun between them to create a soundproof ceiling sandwich, or line the inner surface of a single drywall layer with super-dense mass loaded vinyl (MLV). (See greengluecompany.com for instructions on applying Green Glue.)

At densities of up to 2 pounds per square foot, MLV is the next best thing to lead. It's sold by the yard in rolls, like carpeting, and it is installed in much the same way. As a result, it is often used to soundproof floors -- though some retailers advocate their own brands of high-density floor coverings, often made from recycled materials. If you do opt for MLV, be sure to lay it atop a thin layer of foam or felt; it only works if it has been "decoupled" from the underlying surface.

And remember to tape the seams between adjacent strips to prevent sound leakage.

Unfortunately, any floor treatment will be unsightly, so you'll only want to go this route if you don't mind covering the whole shebang with carpeting -- not to mention losing sight of your hardwood floors.

Doors and windows are often the weak links in a soundproofed room. Still, there are a few things you can do to improve them.

First, replace any hollow-core doors, which are almost transparent to sound, with heavier solid-core ones. Next, install acoustic seals (basically, fancy weather-stripping) around the door frames to prevent sound from flowing around the doors like water through a cracked glass. For additional peace of mind, install automatic door bottoms, which use spring-loaded mechanisms to drop sound-stopping neoprene seals onto the floor every time you close the door.

Windows, alas, are less amenable to a DIY approach. Installing double or triple-glazed models, as some home-improvement types recommend, won't necessarily do the job, because such windows may only block certain frequencies -- and not the ones that are driving you crazy.

The best solution is to install a second soundproof window behind your existing one, trapping a layer of air between the two. Several companies manufacture such contraptions using sound-blocking materials and high-quality seals, and most claim to block up to 95 percent of the noise that passes through ordinary glass.

Depending on the precise nature of your noise problem, taking any one of these measures should offer some relief.

Taking all of them will almost guarantee a quiet zone. So go ahead -- recycle those egg cartons, and donate that old mattress to the local second-hand store.

You won't miss them.

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Soundproof resources

- Several manufacturers produce soundproof drywall. One of the most commonly recommended is QuietRock, made by Quiet Solution (www.quietsolution.com; 800-797-8159). Expect to pay just over $65 for a basic 1/2-inch, 4-by-8-foot panel from a local distributor like Zechman Supply (430 N. Damen Ave, Chicago; 312-733-6600).

- Green Glue can be purchased directly from the Green Glue Co. in West Fargo, N.D. (greengluecompany.com; 800-854-2948). A case of 12 tubes costs $177 plus shipping. The company also provides instructions on how to apply the stuff.